The regional distribution of dorsal pontine tegmental neurons expressing cholecystokinin (CCK) messenger RNA (mRNA) was examined using in situ hybridization histochemical techniques. A distribution of neurons containing CCK mRNA was observed in the motor nucleus of the trigeminal nerve a region which has not been shown to contain CCK by immunocytochemical means. In addition, CCK mRNA was seen in the caudal portion of the dorsal raphe nucleus which correlates with prior immunocytochemical observations. The presence of CCK mRNA in the cholinergic motor trigeminal nucleus suggests that these cells express the CCK gene which have gone undetected in previous immunocytochemical studies. It is also suggested that CCK may have an influence on muscular contraction at sites of trigeminal nerve innervation (e.g., muscles of mastication).